High value biological samples are often stored and processed using so-called SBS format racks containing a plurality of test tubes. SBS format racks confer to ANSI/SLAS 1-2004 standards and have a standardized footprint of 127.76 mm±0.25 mm×85.48 mm±0.25 mm but varying number of test tube apertures. Such racks may contain, for example, 96 test tubes in an array of 8 by 12 apertures or wells designed to hold the tubes securely. The test tubes and their contents may be maneuvered in a processing system, for example between a cold store and various processing stations and may be required to be filled (partly or fully) or processed simultaneously or individually.
Conventionally, capping and de-capping of test tubes has either been carried out by hand or else by means of a capping and de-capping unit one test tube at a time, either while the test tubes are still held in the rack or after they have been separated from the rack. This is not only tedious (particularly in the case of manual capping and de-capping), but also slow as it is usual for multiple tubes to require processing in the same way at the same time.
Solutions (e.g. EP 1882949 or WO 2014023683) are known for capping and de-capping test tubes in standard laboratory test tube racks, such as e.g. the aforementioned SBS format test tube racks.
Automated capping and de-capping of screw cap test tubes involves mechanisms to create a rotational and opposite relative movement of screw cap and test tube. To this purpose both the screw cap and the test tube must be kept from slipping and co-rotating during the capping and de-capping operations. Most automated capping and de-capping devices exert a slight pressure on the screw cap and test tube assemblies during the capping and de-capping operations, thereby increasing the friction force of test tube to test tube rack. However, for many uses and test tubes this slight pressure is not sufficient to keep a test tube from co-rotating with its screw cap. This problem so far has limited the uses of automated capping and de-capping unnecessarily.
WO 2014023683, which is hereby incorporated by reference, discloses a capping and de-capping apparatus 100 (FIG. 4) for capping and de-capping capable tubes 112 disposed in a rack 111 with a two dimensional array of apertures for holding said tubes, the apparatus comprising a rack support 110 for supporting the rack; a head unit 120 supporting a two-dimensional array 121 of capping and de-capping grippers 122, each capping and de-capping gripper including a capping and de-capping socket unit 123 configured for engaging and retaining a cap 113, the capping and de-capping grippers 122 being aligned with tube apertures defined by the array in the rack; a drive mechanism 130 for moving the rack support 110 and head unit 120 relatively towards and away from one another, to cause engagement or disengagement of at least one capping and de-capping socket unit 123 with or from a cap 113 of at least one tube 112; and a drive system for rotating at least one capping and de-capping gripper 122 and the capping and de-capping socket unit 123 attached thereto, wherein rotation of the capping and de-capping socket unit, after engagement of the at least one capping and de-capping socket unit with at least one cap 113, causes attachment of the at least one cap to the at least one tube 112 within the rack 111 when the at least one capping and de-capping gripper 122 rotates in one direction and causes detachment of the at least one cap from the at least one tube when the at least one capping and de-capping gripper rotates in the opposite direction, characterized in that the at least one capping and de-capping gripper 122 has a throughgoing passage extending through the at least one capping and de-capping gripper and the capping and de-capping socket unit 123 attached thereto, an ejector pin moveably arranged within the through going passage; and wherein the ejector pin is configured to perform a translational movement relative to the at least one capping and de-capping gripper 122 and capping and de-capping socket unit 123 attached to the gripper thereby effecting a release of a cap retained within the capping and de-capping socket unit. The apparatus 100 further includes a drive system 150 and a control unit 160. The capping and de-capping apparatus of WO 2014023683 is particularly suitable for both individual and simultaneous capping and de-capping of test tubes of tubes which are rotationally restrained by the rack during the automated capping and de-capping operations.
In order for the test tubes to be easily inserted and retracted from a standard rack, the apertures or wells are often designed with a slight clearance or positive tolerance, such that the test tubes do not encounter any friction restriction upon being inserted and retracted from the standard rack.
Standard racks offering friction restrictions over the entire well surface are also well-known in the art, such as e.g. standard racks made from polystyrene foam or injection molded plastics, both types of racks having small negative tolerances, with the small negative tolerance offering sufficient resistance to insertion and retraction of the test tube without blocking the movement of the test tube completely.
A problem in automated capping and de-capping of test tubes in standard racks is that currently existing standard racks are not all equally suitable for use in automated capping and de-capping. Particularly, it is a necessary requirement of the assembly of the test tube inside a standard rack that there is sufficient friction between test tube and standard rack to counteract the torsional forces exerted on the test tube by the automated capping and de-capping device during the capping and de-capping operations. For this reason, standard racks having negative tolerance well sizes are typically employed in automated capping and de-capping of test tubes, as they are particularly suited for providing the necessary friction force.
However, for various reasons, not all test tubes are suitable for use in automated capping and de-capping with a standard rack having a negative tolerance well size. E.g. tapered, in particularly conically tapered, test tubes are easily insertable and retractable from negative tolerance wells, in particularly since either the well or the test tube, or both, are usually designed to be slightly deformable under the pressure of insertion. Such test tubes therefore are well suited for automated capping- and de-capping. However, test tubes which are e.g. smooth, brittle, overly deformable (e.g. blow-molded test tubes), flat-bottomed etc. are currently difficult to automatically cap and de-cap in standard SBS test tube racks.
A current solution to some of the problems detailed above (cf. http://biosero.com/capping-decapping/vialcap24/—including a YouTube video clip, visited Jan. 26, 2015); combines a customized SBS format rack with an automated capping and de-capping device (VialCap24, Biosero) for use with flat bottomed glass vials comprising screw caps. The capping and de-capping operation displayed at the home page and in the video clip involves clamping of all screw caps in a cap holder and simultaneously rotation of the glass vials in the customized SBS format rack coupled with an upward (de-capping) or downward (capping) motion of the cap holder. Rotation of the glass vials is effected by a plurality of rotation wheels operating simultaneously. The rotation wheels exert a friction force on the glass which during operation (as can be seen from the video clip) is large enough to rotate the glass vials while also being large enough to hold the vials in the rack during the movement of the cap holder upwards during the de-capping operation. From the video clip it appears that the glass vials are pinched or clamped between at least two, but apparently between four rotation wheels during the de-capping operation displayed, thereby increasing the friction between the rotation wheels and the glass vials during the de-capping.
This customized SBS format rack can (according the homepage) be made from metal (aluminum) or plastics (PTFE) and is constructed as a two tier assembly with a top tier having a standard SBS format rack layout with circular holes for the glass vials and a bottom tier consisting of a net-like structure of open quadratic tiles having solid metal or plastic borders between tiles, and the tile surfaces being void of material to allow the aforementioned rotation wheels to protrude through the open tiles during operation of the de-capper and contact the vials on their rounded sides. The two tiers are attached on a frame structure whereby the tiers become spaced apart by a distance of about a third of the length of the glass vial and screw cap. The construction of the rack and use with the intended capping and de-capping apparatus makes this rack unsuited for uses where only individual capping and de-capping is intended.
The present invention concerns a SBS-standard test tube rack which is suitable for use in automated capping and de-capping of flat bottomed test tubes, in particular of flat bottomed glass vials, both for individual test tube capping and de-capping as well as simultaneous capping and de-capping of all test tubes in the aforementioned SBS-standard test tube rack, in particular being suitable for use with the automated capping and de-capping apparatus detailed in WO 2014023683.